Abstract: To better understand why some mothers talk to their children about sex and others do not, we examined the role of two social cognitive variables- self-efficacy and outcome expectancies- in explaining sex-based communication. The present study was part of a larger study to test the efficacy of two HIV prevention programs for mothers and their adolescents. Mothers and their adolescents were recruited from a large community organization that serves youth who live in disadvantaged circumstances. The sample for the present study included 486 mothers who averaged 38.4 years of age (SD = 6.73). The majority were African American (97.7%), not married (66.7%), and had a high school degree (89.5%). Their adolescents ranged in age from 11 through 14 years of age and most were male (61.3%). The results of the analysis revealed that mothers who expressed higher levels of self-efficacy and more favorable outcomes associated with talking to their children about sex were more likely to do so. In a regression analysis, we learned that the mother’s degree of efficacy beliefs, along with her expected outcomes associated with talking about sex, the importance of religious beliefs to her, and the age and sex of her adolescents were important factors associated with talking with them about sex.